Rotary cutter for drills



Sept. 8, 1953 o oN 2,651,501

ROTARY CUTTER FOR DRILLS Filed Feb. 15 1951 INVENT RICHARD D. MC MAHOATTORNEYS Patented Sept. 8, 1953 UNITED not. a,

PATENT omen 2 claims; (01. 25541):

The present invention relates to rotary boring tools and; moreparticularly, to shale and rockbits for usein drilling through hard;medium or soft formations.

An important object consists in providing: an 5 improved cone-shapedroller cutter for drilr bits having means for detachablyconnecting'orlocking each of the cones to the bit spindle on the"outside of the bit so as to prevent thrust or'strai'n beingappliedagainstthe body of the bit.

A further objectconsists in provid-ing" mumstan'tiallycone-shaped'cutter with teeth arrangedin axially spaced rowsthat progressively increase diameter" from the front to therear endsthereof so that the row of largest diameter is positionedadjacent-the'b'ody" of the bitw Addi tionally, the teeth of the" cutterareso shapedand arranged as to" be self-sharpening and'self cleaningduring the operation of the bit and may be set or'adjustedat differentangles relative to the vertical'axis of the bit.

A" further object consists in providing-5 a shale" and rock bitwithmeans for insuring the-drilling of astraight hole a'nd in which thewater jets are? located in the'lower portion of the bit body.

A still further object comprherids the provi sion of a substantiallycone-shapedcutter for-- drillbits in whichthecutte'r head-*is'preferabhrformed-with a shell and an interfittin'g locking collar to which theshell is detachably'connected.- Additionally, the sectional cutter is=revolublymounted on a'-' downwardly inclined spindle carried by the bitthrough aball beairing-cohnc tion that functionstorevo1ubly'maintain-*the"- cutter'onthe spindle but which permits the"ready and quick removal of the shell section from thecollar sectionsothat the cutter head may be changed or a new one substitutedwithout'throw ing away or destroying the whole'bit assembly:

Other-objects a'ndadvantages ofthe' invention" will become apparent fromthe fol1owing'=de'scrip=' tion when-taken in conjunction with the-accompanying claims and drawings:

Referring to the" drawings-wherein is-"showriat preferred embodimentofthe invention;

Figure 1 isa'side elevationalview of a-rollercutter bit constructedinaccordance with the present invention and'with parts insectionterclearness of illustration".

Figured is a-front endview of Figural Figure 3 is a disassembledview'o'f a'retai-ning spindle and its associated lock'ing" collar; aridFigure i is a detail sectional view or a cutter tooth constructedmascara-ante with the pres'ent invention.

Referringto the drawings in which like nuo morals indicate like parts inthe several views, In generally indicates a -rotary shale and rock bithavin alower round or curved hollow head H and an upwardly externallythreaded tubular shank- 92' which may be connected to the head throughan; intermediate smooth curved or reduced portion l3; Thethreaded'shankl2 may be'tapered"and'is-arranged to be'det'achably connected to a'rotary drill collar or drillstem so as torotate therewith during theoperation of the bit: The'head II is" provided with two or moredownwardly inclined fiat smooth surfaces M (Fig. 1 y which vary innumber inaccordance 5 with -the-number of cuttersto-be associatedwiththe bitr As showni the head II? is formed with two diametrically opposeddownwardly inclined fiat surfaces I 4; each of'which has extendingoutwardly and downwardly therefrom, an inclined 9supportingspindle oraxle I5 which may be con n'ectedto the bit in any suitable-manner.Preferably, the head 1 l' is formed with inclined open-- ings -l 6"whichextend inwardly and-centrally from thefia-t surfaces It and converge atsubstantially ,the" axial or-vertical-center of the head I I. Thespindles l5 -extend-into the'openings ISso' that their inner endsarebrought intoabutting engagement as-at [1- (Fig: 1')- in order toabsorb thethrust of each other; during the; operation of'theacutterzpEa'Ch"Qf1th8"' spindles I5 is main-' tained in" a fixed position with-inan opening I 6' inanysuitable manner suchasby the spaced spot welds- 5.The innerabutting ends of the-spindle- |5 is eachprovided with acomplementary semi- IS arranged-inaXiaIIy spaced rows 26;21 and-22 (Fig.-1)- which may bewariedin number as the particular operating conditionsrequire;- Eachrow=of teeth-'comprisesa b'ase'23 (Fig; 4). It

45 will *be' notedthatthe rows of teeth progressively increase indiameterfronrthe outer row 26 to the-inner row" 22' so as -to impart acone shape to 'th'e=cutter; and the teeth in each row"arecircumferentiall-v'spaced apart and of substantiallyablyisfornied-ofanouter shelli l (Fig; 1 hav inga central longitudinallydisposed recess 7 25; the bottom or inner wall of which is curvedas at"26170 receive a" ball bearing *2? that "also 'fits" 55-1nto acomplementary? recess *26 (Fig. i 3') in the adjacent end of the spindle15. The inner wall of the recess 25 is formed with an annular segmentalportion or curved surface 28 which terminates in an outwardly disposedenlarged tapered threaded portion 29 that extends to the inner end ofthe cone. An annular member or look ring 30 is provided with anexternally tapered threaded surface 3| (Fig. 3) arranged to engage thethreads 29 of the cone and is formed on its outer or reduced end with anannular segmental surface 32. The retaining spindle intermediate itslength has an externally disposed annular groove 33 which constitutes arace for the ball bearings 34, which when the parts are assembled(Fig. 1) also engages the segmental surfaces 28 and 32 that coact withthe groove 33 in order to rotatably mount the cutter l8 on the spindlel5 and lock the cutter to the spindle so as to pre- 3 through mediumformations, smaller teeth but vent its accidental axial removaltherefrom. The

ball bearin 21 is preferably of such diameter as to provide a space orpassage 35 between the wall of the recess 25 and the cylindrical portion36 of the spindle IS. A radial passage 3! extends outwardly from thecurved surface 28 and between the rows 2! and 22 and may be providedwith a Zerk connection so as to introduce a suitable lubricant such aswaterproof grease into the bearing surfaces of the rotary cutter. Thelock ring 30 is spaced from the spindle l5 and has its inner wallprovided at one end with an annular recess 38 in which is mounted agrease retaining packing 39, preferably of wedge shape, so that as thepressure is increased thereon by the plug 30, it will form a tighterseal with the adjacent smooth surface of the spindle in order to prevententrance of drilling mud or escape of grease from the cutter. Thus,means are provided for rotatably mountin the cutter on the spindle andpermitting removal of the shell section 24 from the lock ring 30, sothat the shell may be replaced when worn out, without disturbing thering, ball bearings 34 or other parts of the bit assembly. Additionally,the packing 39 coacts with the seal produced by engagement of the lockcollar with the ball bearings and the inner wall of the cutter so as topreclude the possibility of mud and other foreign matter working its wayinto the bearing surfaces of the cutter. The diameter of each of theball bearings 28 is such that the annular groove 33 is substantiallysemi-circular relative to the ball bearings, while the curvature of thesurfaces 28 and 32 are each a quarter of the same circle so as to coactwith the groove 33 to completely enclose the ball bearings when theparts are assembled, and thus prevent the axial removal of the cutterfrom the spindle. The head I I of the bit between the flat sides 14 andin its bottom may have any number of outwardly extending passages oropenings 40 which communicate through the tubular member or shank 12with the drill in order to supply fluid or water to disintegrate theearth or material during the drilling operation.

The teeth [9 of each row on the cutter 18 are so designed and shaped asto be self-sharpening and self-cleaning durin the operation of thedrill, and each tooth extends outwardly and radially from its base 23 soas to form converging solid opposed sides 4| and 42 (Fig. 1) which mergeinto the curved cutting edge 43 that starts at the base 23 and extend ortaper upwardly in the manner as shown in Figure 4 to the apex 44 of thetriangular-shaped end portion 45 that likewise extends upwardly from thebase 23 in more of them are provided. When drillin through hardformations, still smaller teeth and of a larger number or employed. Therows of teeth of different size and number are cut in differentdiameters so that the cuts in the formation or earth are staggered. Whenthe parts are assembled, it will be seen that the spindles extenddownwardly and outwardly from the body H of the bit and the cutters arerevolubly locked on the spindles completely on the outside of the bitbody. Additionally, the spaced passages 43 discharge a jet of fluid atan angle across the face of the body II and down over each corner so asto clean the same and wash out the cuttings.

In assembling the bit structure, each of the spindles I5 is threadedinto its adjacent socket l l. The ball bearing 2'! is positioned in itscurved socket 26 and the ball bearings 34 and the shell 24 arepositioned so as to fit on the spindle; The lock collar 30 is thenthreaded into the shell until the curved surface 32 thereof is broughtinto engagement with the ball bearings 34. The

shell 24 and the collar 29 are now rotatably mounted on the spindle I5,but are prevented from being axially removed therefrom due to thelocking connection effected by engagement of the ball bearings with thesemi-circular groove 33 and the segmental curved surfaces 28 and 32.However, the shell 24 may be unthreaded from the collar 29 withoutdisturbing any of the other parts of the cutter assembly. Consequently,when the teeth of a cutter are Worn out, the cutter is not completelydiscarded or thrown away since it may readily be replaced by a new shellwhile retaining the same look collar and may be installed at a minimumexpenditure of time, labor and cost. The shape of the cutters and thearrangement of the rows of teeth in progressively increasing diameterstoward the adjacent flat sides I4 allows the cone-shaped cutter to beplaced on the body of the bit so that the cutters l8 will revolve on thespindles and be brought into cutting engagement with the earthformation, such as shale, so as to cut or reduce it to small particlesthat are forced out of the hole by the streams of water passing downthrough the spaced passages 40. The teeth of the cutter [8 are formed onthe shell 24 so that when it is desired to replace the teeth, the shellis unscrewed from the collar 29 and a new shell is applied or connectedto the lock ring so as to be revolubly mounted on the spindle by theball bearings 21 and 34 in the manner as previously described. Properlubrication of the bearing surfaces is provided through the passage 31,through which any suitable waterproof grease or lubricant may beintroduced. It will be seen that the present invention provides asimple, efficient and economical bit structure in which, when the teethbecome worn, they may the form of a pyramid. The spaced straight linesbe readily and economically replaced as contrasted to being discarded aswas heretofore the custom.

The size and number of rows of teeth on each shell or cutter may bevaried. The position of the teeth during the drilling operation is suchthat the bottom of each tooth engages the formation first and thecutting edge 43 then knifes its way through the formation. As the twooutters on opposite sides of the body ll of the drill are inclinedinwardly toward each other (Fig. 1) and converge toward the longitudinalcenter of the bit, it will be seen that during the drilling operation,the earth or material as it is cut or sheared, is crowded or forcedtoward the center of the hole in the paths of the streams of waterdischarging through the passages 40, so as to insure an efficientoperation of the drill. By reason of the taper of the cutting surfacesof the teeth and the connection of the cutters with the bits, means areprovided for preventing the bit from rocking and insures the drilling ofa straight hole. Additionally, the teeth as they are worn, areself-sharpened and self-cleaned so that their life and durability arematerially prolonged. When the teeth do become worn, they may be readilyreplaced by withdrawing the shell from its locking ring and substitutinga new shell thereof. Thus, a substantial saving is effected since only aportion of the cutter has to be replaced as contrasted to. throwing awaythe complete cutter as was heretofore customary. It will be manifestthat three or four spaced outers I8 may be connected to the head I I bysimilarly formed spindles l5, and that the size and number of cuttersemployed will be determined by the particular type of formation withwhich the bit is to be used. The teeth I9 in each row are so disposedand formed that the curved cutting edge 43 extends upwardly from infront of the pyramidal end of the adjacent tooth. The upper end of thecutting edge terminates at the apex of its triangular front end, so thatthe teeth provide cutting surfaces of maximum solidity and strengthwhich extend completely over the area of the cone to insure efficientoperation and removal of the shale or formation from the hole.

The form of the invention shown is merely illustrative and it will beunderstood that such changes may be made as come within the scope of thefollowing claims.

I claim:

1. A rotary drill bit having a head at the lower end thereof, said headbeing provided with spaced, fiat, downwardly converging sides, each ofsaid flat sides having a downwardly inclined spindle extending outwardlytherefrom, each spindle intermediate its ends having an annular groovepositioned outside of said head, a substantially cone-shaped cutterrevolubly mounted on said spindle, said cutter including a shell sectionand an interfitting collar section spaced outwardly from said head, saidshell section having an internally threaded inner end portion, saidcollar section having an externally threaded surface engaging saidthreaded end portion, said sections adjacent said annular groove havingsegmental opposed surfaces, ball bearings mounted in said annular grooveand engaged by said segmental opposed surfaces in order that each cutteris locked to the spindle on the outside of said head, said cutter havinga passage therein communicating with said ball bearings for supplyinglubricant thereto, and a packing between the collar section of thecutter and the spindle to prevent entering of drilling mud into the ballbearings and the escape of the lubricant therefrom.

2. A rotary drill bit having a head at the lower end thereof, said headbeing provided with spaced, flat, downwardly converging sides, each ofsaid flat sides having a downwardly inclined spindle extending outwardlytherefrom, each spindle intermediate its ends having an annular groovepositioned outside of said head, a substantially cone-shaped cutterrevolubly mounted on said spindle and spaced outwardly from said head,said cutter including a shell section and an interfitting collarsection, said shell section having an internally threaded end portion,said collar section having an externally threaded surface engaging saidthreaded end portion, said sections adjacent said annular groove havingsegmental opposed surfaces, ball bearings mounted in said annular rooveand engaged by said segmental surfaces so as to prevent axial removal ofthe cutter from the spindle, said cutter having a passage for conductinglubricant to said ball bearings, a packing between said collar and saidspindle, said packing preventing introduction of drilling mud into theball bearings and the escape of the lubricant therefrom, the parts beingarranged so that the cutter is completely locked to the spindle on theoutside of said head, and means for supplying liquid into and throughthe bit to clean the teeth durin the operation of the drill.

RICHARD D. MCMAHON.

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